The present invention relates to an image recording system having therein a halftone dot image data producing apparatus which produces halftone dot image data and outputs them, an image recording apparatus which records a halftone dot image on a photosensitive material in accordance with halftone dot image data, and a halftone dot image data storing apparatus which stores halftone dot image data produced by the halftone dot image data producing apparatus and outputs the halftone dot image data to the image recording apparatus, and to the halftone dot image data storing apparatus.
In recent years, due to popularization of desk top publishing, there have been generalized an operation wherein images inputted from a scanner are subjected to image editing on a software of a computer and are paginated, and editing on a full digital basis has lost its novelty.
In the process of this sort, there are conducted image setter output wherein page-edited image data are directly outputted on a film, CTP (computer to plate) output wherein image recording is directly conducted on a printing plate, and CTC (computer to cylinder) wherein image recording is directly carried out on a printing plate which is wound around a cylinder of a printing machine, all for improving efficiency.
In this case, when output on a film or output on a printing plate is conducted only for confirmation of proofreading, and printing proofreading and other proofreading with other materials are conducted, there is caused a problem that films and printing plates are wasted and extra works are required.
Accordingly, in the process of this kind wherein image forming and image editing on a full digital basis are conducted by a computer, in particular, there is demanded a system to directly conduct color image output which is called DDCP (direct digital color proof).
In such DDCP, a color proof which reproduces output shown by digital image that is processed on a computer is prepared to confirm a pattern, an image color, a composition and letters and characters, before recording on a plate-making film with an image setter from digital image data processed on a computer, or before conducting final printing work to prepare a printing plate directly by CTP, or before conducting image recording with CTC directly on a printing plate wound around a cylinder of a printing machine.
In the process of proofreading in this printing process, a color proof is prepared and used for the following three applications.
1) Confirmation of errors in a job site, namely internal correction
2) External correction submitted to an orderer and a designer for confirmation of finish, and
3) Print samples supplied to an operator of a printing machine as a final sample of printed matters
In this case, for internal confirmation and for a part of external correction, there are used proofreading materials incapable of reproducing a halftone dot image, namely, proofreading by a sublimation transfer system, and an occasion to use an outputted object from ink jet and electrophotography, because of needs such as shortening of delivery time and cost reduction. However, for the purpose of confirmation of reproducibility of highlight and details, and of confirmation of interference fringes representing improper phantom image called moire in printing, there actually is strong demand for a proof which can reproduce printed halftone dots faithfully.
Therefore, as an image recording system which makes such color proof as that stated above, there has been proposed an image recording system which has therein a halftone dot image data producing apparatus which produces halftone dot image data and outputs them, an image recording apparatus which records a halftone dot image on a photosensitive material in accordance with the halftone dot image data, and a halftone dot image data storing apparatus which stores halftone dot image data produced by the halftone dot image data producing apparatus and outputs halftone dot image data to the image recording apparatus.
As the image recording apparatus mentioned above, there has been proposed an image recording apparatus having therein a drum on which a photosensitive material can be fixed on the outer circumferential surface, a rotation driving mechanism which rotates the drum and an optical unit which exposes a photosensitive material fixed on the outer circumferential surface of the drum in accordance with image signals, and a sub-scanning mechanism which moves the optical unit in the direction which is in parallel with the rotation axis of the drum, wherein the photosensitive material is fixed on the drum, then the photosensitive material fixed on the outer circumferential surface of the drum is subjected to exposure by the optical unit in accordance with image signals while the drum is being rotated by the rotation driving mechanism, and the optical unit is moved by the sub-scanning mechanism in parallel with the rotation axis of the drum to record a halftone dot image on the photosensitive material fixed on the outer circumferential surface of the drum.
In this case, the halftone dot image data producing apparatus outputs halftone dot image data for each color in succession, but exposure is conducted simultaneously for plural colors on the image recording apparatus. Therefore, it is necessary to stock halftone dot image data temporarily. In the past, in this case, halftone dot image data equivalent to several times of main scanning are made in succession, and halftone dot image data equivalent to several times of main scanning are stored temporarily, then they are sent to the image recording apparatus where a halftone dot image is recorded.
However, the speed for generating halftone dot image data is not constant, and it sometimes takes more time than expected. In this case, what is stocked temporarily is only halftone dot image data equivalent to several times of main scanning. Therefore, an amount of produced data is not sufficient, which makes image recording to be impossible. In the conventional apparatus, therefore, when generation of data is not sufficient, the image recording apparatus was required to have a function to suspend image recording temporarily. There was further a problem that image recording time was long. Even in the case where the same halftone dot image is recorded on plural sheets of photosensitive material, each sheet required generation of halftone dot image data of raster image format, resulting in a long total image recording time caused by generating time for image data.
The invention has been achieved in view of the problems stated above, and its object is to prevent suspension of image recording by making image data and thereby to make it possible to conduct image recording at high speed by outputting image data at high speed.
The above object can be attained by the following structure.
An image recording system, comprises:
a halftone dot image data producing apparatus to produce and output halftone dot image data corresponding in amount to a single sheet of output image for each of plural colors in succession;
an image recording apparatus comprising
a drum on an outer circumferential surface of which a light sensitive material can be fixed,
a rotation driving mechanism to rotate the drum,
an optical unit to expose the light sensitive material on the drum to plural color light simultaneously in accordance with the inputted halftone dot image data of plural (Nxe2x89xa73) colors, and
a sub-scanning mechanism to move the optical unit in a direction parallel to a rotation axis of the drum, whereby the image recording apparatus records a halftone dot image on the light sensitive material in such a way that the light sensitive material is fixed on the drum, the drum is rotated by the rotation driving mechanism, the optical unit exposes the light sensitive material on the drum to plural color light in accordance with the halftone dot image data, and the sub-scanning mechanism moves the optical unit in a direction parallel to a rotation axis of the drum; and
a halftone dot image data storing apparatus to store the halftone dot image data produced by the halftone dot image data producing apparatus and to output the halftone dot image data to the image recording apparatus, the halftone dot image data storing apparatus comprising plural memory devices each storing the halftone dot image data corresponding in amount to a single sheet for one of plural (N or Nxe2x88x921) colors.
Further, the above object may be attained by the following preferable structure.
In a system to record half tone dot image on a recording sheet made of a color light sensitive material, thereby producing a color proof,
the color proof producing system is characterized in that the color proof producing system comprises
half tone dot image data producing means for producing half tone dot image data;
half tone dot image data storing means for storing the half tone dot image data corresponding in amount to at least a single sheet of a color proof; and
half tone dot image recording means for recording a half tone dot image on the recording sheet on the basis of the half tone dot image data read out from the half tone dot image data storing means,
the half tone dot image recording means including
a rotating hollow drum provided with a plurality of holes passing through from its peripheral surface to its inside, wherein a half tone dot image is form on the recording sheet while the drum is rotated on the condition that the recording sheet is wound and held around the drum, and
pressure reducing means for reducing the inside pressure of the rotating drum,
wherein the recording sheet can be formed in plural different sizes and the rotation speed of the rotating drum is changed in accordance with the size of the recording sheet wound around the rotating drum.
An image recording apparatus, comprising:
a drum;
a rotation driving mechanism to rotate the drum;
a roll setting section to set a roll of a light sensitive material;
a cutter to cut the light sensitive material fed from the roll setting section into a sheet; and
a optical section to irradiating exposure points in plural channel with light from plural light sources; wherein the image recording apparatus records half tone dot image whose pixel density is 1000 dpi or more in such a way that the drum holds the light sensitive material cut by the cutter into the sheet whose sheet width and sheet length are 0.25 m or more, the rotation driving mechanism rotates the drum, and the exposure is conducted in accordance with digital image signals, and
wherein the peripheral speed of the drum at the time of recording an image is 3 m/sec or more, the degree of eccentric of the drum is smaller than 100 xcexcm, and the linear expansion coefficient R1(/K) of the drum and the diameter D (cm) of the drum satisfy the formula xe2x80x9cR1xc3x97Dxe2x89xa60.01xe2x80x9d.